My purpose in adding solar to the Cougar, was to increase the number of days we could stay on-site without hookups. Our 200w Zamp portable offers 10 amps of charging power. We set the portable unit out and leave it out until we're ready to break camp. Our 110v electrical usage is minimal and find that a 750 watt inverter is all we need to run the television, recharge the cell phones miscellaneous batteries and laptop. Total outlay was under $400.
If you are planning to run all your usual 110v accessories then it will be a much more expensive. Larger/more solar panels. Larger/more batteries to store more power. Larger inverter to supply the 110v systems. You'll also need a much more complicated and expensive solar support system i.e. more sophisticated controller and solar to 110v system interface.
We chose to keep ours simple and inexpensive. If you want to go full bore with solar you best have a fully loaded "Buckzooka".
BTW, the limiting factor so far has been the need to empty the black water tank
